TimeMachine Always failing, and possible USB issues?

Well first off, I'm wondering if i have issues with my USB ports. its a mid-2012 15" cMBP.

reason i'm saying that is a few weeks ago i had 2 different USB drives crash and freeze on the mac when i was trying to copy big files on them. it seems like if the USB is under stress for some time, it'll dismount then remount. Not 100% sure though. I was wondering if there's a stress test or something i can do BEFORE my 90-day warranty thing expires.

and for the second part, recently my time machine has been failing ALL the time. Never works anymore. Tried reformatting it, and using different drives.

Here's a copy of the Time Machine Log if anyone can figure out whats wrong.

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